Let's roll up our sleeves and solve this. We have 771 and we're going to multiply it by 7, essentially adding 771 to itself 7 times.
Step 1: 0 + 771 = 771
Step 2: 771 + 771 = 1542
Step 3: 1542 + 771 = 2313
Step 4: 2313 + 771 = 3084
Step 5: 3084 + 771 = 3855
Step 6: 3855 + 771 = 4626
Step 7: 4626 + 771 = 5397

So, 771*7 = 5397